New salts useful as corrosion inhibitors

ABSTRACT

Salts having the formula: 
     
         Y--NH.sub.3.sup.+.RCO.sub.2.sup.-                          I 
    
     in which Y is a group of formula R 1  XCH 2  CH(OH)CH 2  --, R and R 1  are the same or different and each is a straight- or branched chain alkyl group having from 1 to 18 carbon atoms, a straight- or branched chain alkenyl group having from 2 to 18 atoms, a cycloalkyl group having from 4 to 12 ring atoms, an aryl group having 6-10 ring atoms, or an aralkyl group having from 7 to 10 carbon atoms; and X is O, CO 2 , NR 2  or S and R 2  is hydrogen, a straight- or branched chain alkyl group having from 1 to 18 carbon atoms or an alkenyl group having from 2 to 18 C atoms.

The present invention relates to new salts; to processes for theirproduction; and to their use as corrosion inhibitors for metals innon-aqueous fluids.

Water can be present, as a contaminant, in the systems containing suchfluids. As a consequence of the presence of this water, corrosion ofmetals, especially ferrous metals, in contact with such systems, is aserious and costly problem.

A particular aspect of this problem is the rusting of ferrous metals ininternal combustion engines, steam turbines, hydraulic systems, oilpipelines, storage vessels and the corrosion caused during machiningoperations.

Previous attempts to overcome this problem have involved the use, ascorrosion inhibitors, of

(a) the reaction product of a substituted succinic acid and an alkyleneoxide (U.S. Pat. No. 2,962,443);

(b) a mixture of (i) a 7-44C polycarboxylic acid having 2 or 3 carboxylgroups, or a partial ester thereof with a 1-18C aliphatic alcohol and(ii) an aliphatic tertiary amine having three hydrocarbon groups, eachof which has at least 1-20C atoms and at least one of which has 6-20Catoms, the weight ratio of (i) to (ii) being from 95:5 to 5:95 (U.S.Pat. No. 3,720,615); or

(c) a liquid dicarboxylic acid having the formula: ##STR1## in which xand y are integers from 3 to 9, the sum of x and y being 12, and Z is Hor COOH; as well as mono- or bis alkanolamides of said dicarboxylicacid, or a monoalkanolamide derivative of a soap of said dicarboxylicacid (GB No. 1439899).

Moreover, Japanese Patent Publication No. 15783/1973 describes a rustinhibitor consisting of a derivative of a gamma-alkoxypropylamine havingthe formula:

    R--O--CH.sub.2 CH.sub.2 CH.sub.2 NH.sub.2

in which R is an alkyl group. More particularly, it relates to a methodof inhibiting rusting of metals by dissolving a reaction product of agamma-alkoxypropylamine and a fatty acid in water or oil, at elevatedtemperature, preferably 120°-140° C.

Surprisingly, we have now found that certain salts, produced fromstarting materials very similar to those employed in Japanese PatentPublication No. 15783/1973, unexpectedly have superior effectivity ascorrosion inhibitors in such media, when compared to the said Japaneseinhibitors.

Accordingly, the present invention provides salts having the formula(I):

    Y--NH.sub.3.sup.⊕.RCO.sub.2.sup.⊖              (I)

in which Y is a group of formula R¹ XCH₂ CH(OH)CH₂ --, R and R¹ are thesame or different and each is a straight- or branched chain alkyl grouphaving from 1 to 18 carbon atoms, a straight- or branched chain alkenylgroup having from 2 to 18 carbon atoms, a cycloalkyl group having from 4to 12 ring carbon atoms, an aryl group having 6-10 ring carbon atoms oran aralkyl group having from 7 to 11 carbon atoms; and X is O, CO₂, NR²or S and R² is hydrogen, a straight- or branched chain alkyl grouphaving from 1 to 18 carbon atoms, or an alkenyl group having from 2-18Catoms.

When R and/or R¹ and/or R² is a C₁ -C₁₈ straight- or branched-chainalkyl group, they may be e.g. methyl, ethyl, n-propyl, isopropyl,n-butyl, isobutyl, s-butyl, t-butyl, n-pentyl, n-hexyl, n-heptyl,n-octyl, isooctyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl,n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl or n-octadecyl.

When R and/or R¹ and/or R² is a C₂ -C₁₈ straight- or branched-chainalkenyl group, they may be e.g. vinyl, propenyl, but-3-enyl, pentenyl,hexa-2,4-dienyl, octa-2,6-dienyl, decenyl, deca-1,3-decenyl, oleyl orlinoleyl. Such alkyl or alkenyl groups may also be interrupted by one ormore heteroatoms e.g. O, S or by an NH group.

When R and/or R¹ is a cycloalkyl group they may be e.g. cyclobutyl,cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl,cyclodecyl, cycloundecyl or cyclododecyl.

When R and/or R¹ is a C₆ -C₁₀ aryl group, they may be e.g. phenyl ornaphthyl.

When R and/or R¹ is an C₇ -C₁₁ aralkyl group they may be e.g. benzyl, α-or β-phenethyl, α,α-dimethylbenzene or 1- or 2-naphthylmethyl.

When R and/or R¹ is a cycloalkyl, aryl or aralkyl group, they mayoptionally be substituted by one or more 1-4C alkyl groups, hydroxylgroups, amino groups or carboxyl groups.

Preferred salts of formula I are those wherein R is a straight- orbranched chain C₁ -C₁₈ alkyl--(more preferably C₁₀ -C₁₈) or 2-18Calkenyl group and Y is a group R¹ XCH₂ CH(OH)CH₂ -- in which X is O orCO₂ and R¹ is straight- or branched chain C₁ -C₁₈ alkyl group.

More preferred are those salts of formula I wherein the total carbonnumber is between 15 and 39, especially between 23 and 39. Salts havinga carbon number within these limits provide excellentcorrosion-inhibiting activity combined with good solubility innon-aqueous functional fluids.

The new salts of formula I may be produced by forming a salt preferablyby simply mixing an amine having the formula Y--NH₂ wherein Y has itsprevious significance, with an acid of formula RCO₂ H.

The mixing is conveniently effected at ambient temperature. Any heatingapplied is preferably to a temperature below 100° C.; preferably from20°-40° C. and only that required to produce a homogeneous mixture ofthe amine and acid salt precursors.

The mixing may be effected in an inert solvent if desired e.g. in anaromatic hydrocarbon e.g. toluene.

The weight ratio of amine to acid may be in the range of from 1:3 to 3:1but a weight ratio of substantially 1:1 is preferred.

Examples of amines of formula YNH₂ include the following:

X=O

    CH.sub.3 OCH.sub.2 CH(OH)CH.sub.2 NH.sub.2

    C.sub.2 H.sub.5 OCH.sub.2 CH(OH)CH.sub.2 NH.sub.2

    n--C.sub.3 H.sub.7 OCH.sub.2 CH(OH)CH.sub.2 NH.sub.2

    n--C.sub.4 H.sub.9 OCH.sub.2 CH(OH)CH.sub.2 NH.sub.2

    n--C.sub.5 H.sub.11 OCH.sub.2 CH(OH)CH.sub.2 NH.sub.2

    n--C.sub.6 H.sub.13 OCH.sub.2 CH(OH)CH.sub.2 NH.sub.2

    n--C.sub.7 H.sub.15 OCH.sub.2 CH(OH)CH.sub.2 NH.sub.2

    n--C.sub.8 H.sub.17 OCH.sub.2 CH(OH)CH.sub.2 NH.sub.2

    n--C.sub.9 H.sub.19 OCH.sub.2 CH(OH)CH.sub.2 NH.sub.2

    n--C.sub.10 H.sub.21 OCH.sub.2 CH(OH)CH.sub.2 NH.sub.2

    n--C.sub.12 H.sub.25 OCH.sub.2 CH(OH)CH.sub.2 NH.sub.2

    n--C.sub.14 H.sub.29 OCH.sub.2 CH(OH)CH.sub.2 NH.sub.2

    n--C.sub.16 H.sub.33 OCH.sub.2 CH(OH)CH.sub.2 NH.sub.2

    n--C.sub.18 H.sub.37 OCH.sub.2 CH(OH)CH.sub.2 NH.sub.2

    n--C.sub.18 H.sub.35 OCH.sub.2 CH(OH)CH.sub.2 NH.sub.2

    cyclo--C.sub.6 H.sub.11 OCH.sub.2 CO(OH)CH.sub.2 NH.sub.2

    cyclo--C.sub.8 H.sub.15 OCH.sub.2 CH(OH)CH.sub.2 NH.sub.2

    cyclo--C.sub.12 H.sub.23 OCH.sub.2 CH(OH)CH.sub.2 NH.sub.2

    C.sub.6 H.sub.5 OCH.sub.2 CH(OH)CH.sub.2 NH.sub.2

Products from isopropylated phenols as e.g.

    2--i--C.sub.3 H.sub.7 --C.sub.6 H.sub.4 OCH.sub.2 CH(OH)CH.sub.2 NH.sub.2

    4--i--C.sub.3 H.sub.7 --C.sub.6 H.sub.4 OCH.sub.2 CH(OH)CH.sub.2 NH.sub.2

    2,6--Di--i--C.sub.3 H.sub.7 --C.sub.6 H.sub.3 OCH.sub.2 CH(OH)CH.sub.2 NH.sub.2

    3,5--Di--i--C.sub.3 H.sub.7 --C.sub.6 H.sub.3 OCH.sub.2 CH(OH)CH.sub.2 NH.sub.2

    C.sub.10 H.sub.7 OCH.sub.2 CH(OH)CH.sub.2 NH.sub.2

    C.sub.6 H.sub.5 CH.sub.2 OCH.sub.2 CH(OH)CH.sub.2 NH.sub.2

    C.sub.10 H.sub.7 CH.sub.2 OCH.sub.2 CH(OH)CH.sub.2 NH.sub.2

X=CO₂

    CH.sub.3 CO.sub.2 CH.sub.2 CH(OH)CH.sub.2 NH.sub.2

    C.sub.2 H.sub.5 CO.sub.2 CH.sub.2 CH(OH)CH.sub.2 NH.sub.2

    C.sub.9 H.sub.19 CO.sub.2 CH.sub.2 CH(OH)CH.sub.2 NH.sub.2

    n--C.sub.18 H.sub.37 CO.sub.2 CH.sub.2 CH(OH)CH.sub.2 NH.sub.2

X=NR²

    (C.sub.2 H.sub.5).sub.2 NCH.sub.2 CH(OH)CH.sub.2 NH.sub.2

    (CH.sub.3).sub.2 NCH.sub.2 CH(OH)CH.sub.2 NH.sub.2

    (C.sub.6 H.sub.13).sub.2 NCH.sub.2 CH(OH)CH.sub.2 NH.sub.2

    (C.sub.9 H.sub.19).sub.2 NCH.sub.2 CH(OH)CH.sub.2 NH.sub.2

X=S

    CH.sub.3 SCH.sub.2 CH(OH)CH.sub.2 NH.sub.2

    C.sub.2 H.sub.5 SCH.sub.2 CH(OH)CH.sub.2 NH.sub.2

    C.sub.12 H.sub.25 SCH.sub.2 CH(OH)CH.sub.2 NH.sub.2

    C.sub.18 H.sub.37 SCH.sub.2 CH(OH)CH.sub.2 NH.sub.2

Examples of acids of formula RCO₂ H include the following: acetic acid,propionic acid, butyric acid, pentanoic acid, hexanoic acid, heptanoicacid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid,dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoicacid, hexadecanoic acid, heptadecanoic acid or octadecanoic acid;acrylic acid, methacrylic acid, propenoic acid, butenoic acid, hexenoicacid, heptenoic acid, octenoic acid, nonenoic acid, decenoic acid,undecenoic acid, dodecenoic acid, tetradecenoic acid, hexadecenoic acidor octadecenoic acid; cyclohexane carboxylic acid, cyclooctanecarboxylic acid, benzoic acid or α- or β-naphthoic acid, phenylaceticacid, phenylpropionic acid or α,α-dimethylphenylacetic acid, ornaphthylacetic acid.

The amines of formula Y--NH₂ and the acids of formula R--CO₂ H aremostly known compounds and many are commercially-available. Any newamines or acids within these classes can be prepared by methodswell-known to the art-skilled. For example, the hydroxyamine startingmaterials may be produced by treating, with dilute aqueous ammonia, anepoxy compound of formula: ##STR2## wherein R¹ and X have their previoussignificance.

The new salts of formula I are excellent corrosion inhibitors formetals, especially ferrous metals, in contact with non-aqueous fluidscontaminated with water.

Accordingly, the present invention further provides a compositioncomprising a major proportion of a non-aqueous functional fluid and, ascorrosion inhibitor, a corrosion-inhibiting proportion preferably from0.001 to 5% by weight of a salt of formula I as hereinbefore defined.

The non-aqueous functional fluid may be a lubricating oil e.g. a naturalor synthetic lubricating oil; a refined petroleum product such as a fueloil, diesel oil, kerosene, gasoline or aviation fuel; or a hydraulicfluid e.g. a phosphate-based synthetic oil.

The lubricating oil may be a mineral oil, a synthetic oil or any mixtureof such oils. Mineral oils are preferred and examples of these includeparaffinic hydrocarbon oils e.g. a mineral oil having a viscosity of 46mm² /s at 40° C.; "150 Solvent Neutral" a solvent refined neutralmineral having a viscosity of 32 mm² /s at 40° C.; and "Solventbrightstocks", a high-boiling residue from the process of refiningmineral oil, and having a viscosity of 46 mm² /s at 40° C.

Synthetic lubricating oils which may be present may be synthetichydrocarbons such as polybutenes, alkyl benzenes and poly-alpha olefinsas well as simple di-, tri- and tetraesters, complex esters andpolyesters derived from carboxylic acids and hydroxy compounds.Preferred are dicarboxylic acid esters of formula:

    R.sup.3 --OOC--alkylene--COOR.sup.4

wherein "alkylene" denotes an alkylene residue having from 2 to 14carbon atoms and R³ and R⁴ are the same or different and each is analkyl group having from 6 to 18 carbon atoms.

Tri-esters which are of use as lubricating oil base-stocks are thosederived from trimethylolpropane and C6-C18 monocarboxylic acids ormixtures thereof, whereas suitable tetraesters include those derivedfrom pentaerythritol and a C6-C18 monocarboxylic acid or mixturesthereof.

Complex esters suitable for use as components of the compositions of thepresent invention are those derived from monobasic acids, dibasic acidsand polyhydric alcohols, for instance the complex ester derived fromtrimethylol propane, caprylic acid and sebacic acid.

Suitable polyesters are those derived from an aliphatic dicarboxylicacid having from 4 to 14 carbon atoms and at least one aliphaticdihydric alcohol having from 3 to 12 carbon atoms, e.g. those derivedfrom azelaic acid or sebacic acid and 2,2,4-trimethylhexane-1,6-diol.

If desired the salts of formula I may be used in combination with one ormore additives conventionally employed in non-aqueous functional fluids,e.g. antioxidants, metal deactivators, further rust inhibitors,viscosity index improvers, pour point depressors,dispersants/surfactants and wear resisting additives.

Examples of antioxidants are:

(a) Alkylated and non-alkylated aromatic amines and mixtures thereof,for example, dioctyldiphenylamine, 2,2,3,3-tetramethylbutylphenyl-α- and-β-naphthylamines, phenothiazine, dioctylphenothiazine,phenyl-α-naphthylamine, N,N'-di-sec-butyl-p-phenylenediamine.

(b) Sterically hindered phenols, for example:2,6-di-tert-butyl-p-cresol, 4,4'-bis-(2,6-diisopropylphenol),2,4,6-triert-butylphenol, 4,4'-methylene-bis-(2,6-di-tert-butylphenol).

(c) Alkyl-, aryl- or alkarylphosphites, for example: trinonylphosphite,triphenylphosphite, diphenyldecylphosphite.

(d) Esters of thiodipropionic acid or thiodiacetic acid, for example:dilaurylthiodipropionate or dioctylthiodiacetate.

(e) Salts of carbamic and dithiophosphoric acids, for example: antimonydiamyldithiocarbamate, zinc diamyldithiophosphate.

(f) A combination of two or more of the above antioxidants, for example:an alkylated amine and a sterically hindered phenol.

Examples of metal deactivators are:

(a) for copper, e.g. benzotriazole, tolutriazole,tetrahydrobenzotriazole, 2-mercaptobenzothiazole,2,5-dimercaptothiadiazole, salicylidene propylenediamine, salts ofsalicylaminoguanidine.

(b) for lead, e.g.: sebacic acid derivatives, quinizarine, propylgallate.

(c) A combination of two or more of the above additives.

Examples of further rust inhibitors are:

(a) Organic acids, the esters, metal salts and anhydrides thereof, e.g.sorbitan monooleate, lead naphthenate, dodecenylsuccinic-anhydride.

(b) Nitrogen-containing compounds, for example:

I. Primary, secondary or tertiary aliphatic or cycloaliphatic amines andamine salts of organic inorganic acids, for example oil-solublealkylammonium carboxylates.

II. Heterocyclic compounds, e.g. substituted imidazolines andoxazolines.

(c) Phosphorus-containing compounds, for example: amine salts ofphosphoric acid partial esters.

(d) Sulfur-containing compounds, for example, bariumdinonylnaphthalenesulfonates, calcium petroleum sulfonates.

(e) Combinations of two or more of the above additives.

Examples of viscosity index improvers are: polymethylacrylates, vinylpyrrolidone/methacrylate copolymers, polybutene, olefin copolymers,styrene/acrylate copolymers.

Examples of pour-point depressors are: polymethacrylates, alkylatednaphthalene derivatives.

Examples of dispersants/surfactants are: polybutenylsuccinimides,polybutenylphosphonic acid derivatives, basic magnesium, calcium andbarium sulfonates, phenolates and naphthenates. Dispersants are employede.g. in concentrations of 0.1 to 1% by weight, based on the lubricant.

Examples of antiwear additives are:

Compounds containing sulfur and/or phosphorus and/or halogen, e.g.sulfurised vegetable oils, and also monothiophosphates,dialkyldithiophosphates or their zinc salts, tritolylphosphates,chlorinated paraffins, alkyl and aryl disulfides.

The following Examples further illustrate the present invention.

EXAMPLE 1

A salt was produced by mixing 20 grams of dodecanoic acid and 20.3 gramsof 2-hydroxy-3-isoctyloxy propylamine at ambient temperature. A slightexotherm was observed (final temperature 40° C.). The product, a pale togolden yellow oil, showed the IR spectrum characteristic of an aminesalt (--N⁺ H₃ broad centered at 3000 cm⁻¹, --CO₂ ⁻ strong absorption at1542 cm⁻¹)., having the following elemental analysis by weight:

Found: C 68.02; H 12.58; N 3.02%. Calculated for C₂₂ H₄₉ NO₄ : C 67.52;H 12.53; N 3.58%.

EXAMPLES 2 TO 25

In a similar manner, salts were formed from the amines and acids set outin the following Table I:

                  TABLE I                                                         ______________________________________                                        Ex-                                                                           am-                                                                           ple  Amine of formula YNH.sub.2                                                                       Acid of formula RCO.sub.2 H                           ______________________________________                                         2                                                                                 ##STR3##           C.sub.11 H.sub.23 CO.sub.2 H                           3                                                                                 ##STR4##           C.sub.11 H.sub.23 CO.sub.2 H                           4                                                                                 ##STR5##           C.sub.11 H.sub.23 CO.sub.2 H                           5                                                                                 ##STR6##           C.sub.11 H.sub.23 CO.sub.2 H                           6                                                                                 ##STR7##           C.sub.11 H.sub.23 CO.sub.2 H                           7                                                                                 ##STR8##           C.sub.17 H.sub.33 CO.sub.2 H                           8                                                                                 ##STR9##           C.sub.17 H.sub.33 CO.sub.2 H                           9                                                                                 ##STR10##          C.sub.17 H.sub.35 CO.sub.2 H                          10                                                                                 ##STR11##          CH.sub.3 (CH.sub.2).sub.6 CHCHCO.sub.2 H              11                                                                                 ##STR12##          CH.sub.3 (CH.sub.2).sub.6 CHCHCO.sub.2 H              12  i-C.sub.12 H.sub.25 SCH.sub.2 CH(OH)CH.sub.2 NH.sub.2                                             C.sub.17 H.sub.33 CO.sub.2 H                          13                                                                                 ##STR13##          C.sub.17 H.sub.35 CO.sub.2 H                          14                                                                                 ##STR14##          C.sub.11 H.sub.23 CO.sub.2 H                          15                                                                                 ##STR15##          C.sub.11 H.sub.23 CO.sub.2 H                          16                                                                                 ##STR16##          C.sub.17 H.sub.33 CO.sub.2 H                          17                                                                                 ##STR17##          C.sub.17 H.sub.33 CO.sub.2 H                          18                                                                                 ##STR18##          C.sub.17 H.sub.33 CO.sub.2 H                          19                                                                                 ##STR19##                                                                                         ##STR20##                                            20                                                                                 ##STR21##          C.sub.11 H.sub.23 CO.sub.2 H                          21                                                                                 ##STR22##          C.sub.11 H.sub.23 CON(CH.sub.2 CO.sub.2 H).sub.2      22                                                                                 ##STR23##          t-C.sub.9 H.sub.19 CO.sub.2 H                         23                                                                                 ##STR24##          iC.sub.17 H.sub.25 CO.sub.2 H                         24                                                                                 ##STR25##          [(CH.sub.2).sub.4 CO.sub.2 H].sub.2                   25                                                                                 ##STR26##          C.sub.11 H.sub.23 CO.sub.2 H                          ______________________________________                                    

In the above Examples, the I.R. spectra of the salts were consistentwith the structures proposed.

EXAMPLE 26

Several products of Examples 1-25 were tested as rust inhibitors in aturbine grade mineral oil of viscosity 26 mm² /s at 40° C., 4.8 mm² /sat 100° C. and a typical sulphur content of 0.6% using the ASTM D665A(deionised water) and B (synthetic sea water) methods. The test durationwas 24 hours. The results are set out in the following Table II and areexpressed as the concentration (in ppm) of the product which willprevent any trace of rusting of the test spindle.

In both A and B tests, absence of additive caused severe-rusting of thetest spindle to occur.

                  TABLE II                                                        ______________________________________                                                              Minimum concentration (ppm)                             Example Solubility at for zero rusting                                        No.     20° C. weight %                                                                      A test     B test                                       ______________________________________                                         1      >10            <62       125-250                                       2      >10           <125       125-250                                       3      <1                       <125                                          4      <1                       125-250                                       5      <1                       125-250                                       8      <1                       <125                                          9      >10                      >250                                         12      >1            <125       >500                                         13      >10                      250                                          14      >1             125       500                                          15      <1                       500                                          16      >1             125       500                                          17      <1                       500                                          18      <1                       500                                          19      >1                       500                                          ______________________________________                                    

What we claim is:
 1. A composition having corrosion-inhibitionproperties which comprises(a) a major proportion of a non-aqueousfunctional fluid; and (b) an effective amount of a corrosion inhibitorof a salt of formula I

    Y--NH.sub.3.sup.+ RCO.sub.2.sup.-                          (I)

in which Y is a group of formula R¹ XCH₂ CH(OH)CH₂ --, R and R¹ are thesame or different, R¹ is a straight- or branched chain alkyl grouphaving from 1 to 18 carbon atoms, a straight- or branched chain alkenylgroup having from 2 to 18 carbon atoms, a cycloalkyl group having from 4to 12 ring carbon atoms, an aryl group having 6-10 ring carbon atoms, oran aralkyl group having from 7 to 10 carbon atoms; R is a straight- orbranched chain alkyl group having from 7 to 18 carbon atoms, a straight-or branched chain alkenyl group having from 2 to 18 carbon atoms, acycloalkyl group having from 4 to 12 ring carbon atoms, an aryl grouphaving 6-10 ring carbon atoms, or an aralkyl group having from 7 to 10carbon atoms; and X is O, CO₂, NR² or R.sup. 2 is hydrogen, a straight-or branched chain alkyl group having from 1 to 18 carbon atoms or analkenyl group having from 2 to 18 carbon atoms.
 2. A compositionaccording to claim 1 where in the salt of formula I wherein R is astraight- or branched chain C₇ -C₁₈ alkyl- or C₂ -C₁₈ alkenyl group andY is a group of formula R¹ XCH₂ CH(OH)CH₂ -- wherein X is O or CO₂ andR¹ is straight- or branched chain C₁ -C₁₈ alkyl group.
 3. A compositionaccording to claim 1 wherein the total number of carbon atoms in thesalt of formula I is between 15 and
 39. 4. A composition according toclaim 1 wherein the total number of carbon atoms in the salt of formulaI is between 23 and
 39. 5. A composition according to claim 1 whereinthe non-aqueous functional fluid is a lubricating oil, a refinedpetroleum product or a hydraulic fluid.
 6. A composition according toclaim 1 wherein the proportion of the salt of formula I is from 0.001 to5% by weight, based on the weight of the functional fluid.
 7. Acomposition according to claim 5 wherein the lubricating oil is anatural or synthetic lubricating oil.
 8. A composition according toclaim 5 wherein the refined petroleum product is a fuel oil, diesel oil,kerosene, gasoline or aviation fuel.